In the DIY's there is a way to check the proper mixture via the O2 sensor. I'd start with that to get an accurate rating on how rich we are talking here.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k